Methods for on-die memory termination and memory devices and systems employing the same

ABSTRACT

Methods, systems, and apparatuses related to memory operation with on-die termination (ODT) are provided. A memory device may be configured to provide ODT at a first portion (e.g., rank) during multiple communications at a second portion (e.g., rank). For example, a memory device may receive a first command instructing a first portion to perform a first communication and instructing a second portion to enter an ODT mode. The device may perform, with the first portion, the first communication with a host while the second portion is in the ODT mode. The device may receive a second command instructing the first portion to perform a second communication, and the device may perform, with the first portion, the second communication while the second portion remains in the ODT mode. The second portion may persist in the ODT mode for an indicated number of communications, or until instructed to exit the ODT mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/590,096, filed Nov. 22, 2017, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to methods for on-die memorytermination and memory devices and systems employing the same.

BACKGROUND

Memory devices are widely used to store information related to variouselectronic devices such as computers, wireless communication devices,cameras, digital displays, and the like. Information is stored byprograming different states of a memory cell. Various types of memorydevices exist, including magnetic hard disks, random access memory(RAM), read only memory (ROM), dynamic RAM (DRAM), synchronous dynamicRAM (SDRAM), and others. Memory devices may be volatile or non-volatile.Improving memory devices, generally, may include increasing memory celldensity, increasing read/write speeds or otherwise reducing operationallatency, increasing reliability, increasing data retention, reducingpower consumption, or reducing manufacturing costs, among other metrics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram schematically illustrating a memorydevice in accordance with an embodiment of the present technology.

FIGS. 2-5 are simplified timing diagrams schematically illustrating theoperation of memory devices and systems in accordance with embodimentsof the present technology.

FIG. 6 is a simplified block diagram schematically illustrating a memorysystem in accordance with an embodiment of the present technology.

FIGS. 7-10 are flow charts illustrating methods of operating memorydevices and memory systems in accordance with embodiments of the presenttechnology.

DETAILED DESCRIPTION

Memory devices and memory systems can include multipleseparately-addressable memory arrays, ranks, banks, channel, or othersub-divisions of memory capacity. In some such devices and systems,multiple separately-addressable memory portions may have terminalsconnected to one or more common busses (e.g., a data bus, acommand/address bus, a clock signal bus, etc.). To improve the signalquality on a bus during communication with one of theseparately-addressable portions, one or more terminals of anothernon-communicating memory portion may enter an “on-die termination” (ODT)mode, in which the impedance at the one or more terminals of thenon-communicating portion is modified (e.g., to minimize signalreflections or other potentially signal-degrading or noise-contributingeffects).

In some memory systems, a connected host device can indicate to thenon-communicating (e.g., non-targeted) memory portion to enter an on-dietermination mode with a command (e.g., on a command/address bus)addressed specifically to the non-targeted memory portion. Each commandto enter an ODT mode can cause a command decoder of the non-targetedmemory portion to consume power in decoding the command, which cancontribute to a significant increase in the power consumption of amemory system. It is therefore desirable to provide a way to manage theODT modes of a memory system with greater power efficiency.

Accordingly, several embodiments of the present technology are directedto memory devices, systems including memory devices, and methods ofoperating memory devices in which on-die termination can be provided ata second portion during multiple communications at a first portion,without requiring multiple on-die termination commands to be provided toor decoded by the second portion. In one embodiment, a method maycomprise receiving a first command instructing a first memory device toperform a first communication and instructing a second memory device toenter an on-die termination mode, performing, with the first memorydevice, the first communication while the second memory device is in theon-die termination mode based at least in part on the first command,receiving a second command instructing the first memory device toperform a second communication with the memory host, and performing,with the first memory device, the second communication while the secondmemory device is in the on-die termination mode based at least in parton the first command.

FIG. 1 is a block diagram schematically illustrating a memory device 100in accordance with an embodiment of the present technology. The memorydevice 100 may include an array of memory cells, such as memory array150. The memory array 150 may include a plurality of banks (e.g., banks0-15 in the example of FIG. 1), and each bank may include a plurality ofword lines (WL), a plurality of bit lines (BL), and a plurality ofmemory cells arranged at intersections of the word lines and the bitlines. The selection of a word line WL may be performed by a row decoder140, and the selection of a bit line BL may be performed by a columndecoder 145. Sense amplifiers (SAMP) may be provided for correspondingbit lines BL and connected to at least one respective local I/O linepair (LIOT/B), which may in turn be coupled to at least respective onemain I/O line pair (MIOT/B), via transfer gates (TG), which can functionas switches.

The memory device 100 may employ a plurality of external terminals thatinclude command and address terminals coupled to a command bus and anaddress bus to receive command signals CMD and address signals ADDR,respectively. The memory device may further include a chip selectterminal to receive a chip select signal CS, clock terminals to receiveclock signals CK and CKF, data clock terminals to receive data clocksignals WCK and WCKF, data terminals DQ, RDQS, DBI, and DMI, powersupply terminals VDD, VSS, VDDQ, and VSSQ.

The command terminals and address terminals may be supplied with anaddress signal and a bank address signal from outside. The addresssignal and the bank address signal supplied to the address terminals canbe transferred, via a command/address input circuit 105, to an addressdecoder 110. The address decoder 110 can receive the address signals andsupply a decoded row address signal (XADD) to the row decoder 140, and adecoded column address signal (YADD) to the column decoder 145. Theaddress decoder 110 can also receive the bank address signal (BADD) andsupply the bank address signal to both the row decoder 140 and thecolumn decoder 145.

The command and address terminals may be supplied with command signalsCMD, address signals ADDR, and chip selection signals CS, from a memorycontroller. The command signals may represent various memory commandsfrom the memory controller (e.g., including access commands, which caninclude read commands and write commands). The select signal CS may beused to select the memory device 100 to respond to commands andaddresses provided to the command and address terminals. When an activeCS signal is provided to the memory device 100, the commands andaddresses can be decoded and memory operations can be performed. Thecommand signals CMD may be provided as internal command signals ICMD toa command decoder 115 via the command/address input circuit 105. Thecommand decoder 115 may include circuits to decode the internal commandsignals ICMD to generate various internal signals and commands forperforming memory operations, for example, a row command signal toselect a word line and a column command signal to select a bit line. Theinternal command signals can also include output and input activationcommands, such as clocked command CMDCK.

When a read command is issued and a row address and a column address aretimely supplied with the read command, read data can be read from memorycells in the memory array 150 designated by these row address and columnaddress. The read command may be received by the command decoder 115,which can provide internal commands to input/output circuit 160 so thatread data can be output from the data terminals DQ, RDQS, DBI, and DMIvia read/write amplifiers 155 and the input/output circuit 160 accordingto the RDQS clock signals. The read data may be provided at a timedefined by read latency information RL that can be programmed in thememory device 100, for example, in a mode register (not shown in FIG.1). The read latency information RL can be defined in terms of clockcycles of the CK clock signal. For example, the read latency informationRL can be a number of clock cycles of the CK signal after the readcommand is received by the memory device 100 when the associated readdata is provided.

When a write command is issued and a row address and a column addressare timely supplied with the command, write data can be supplied to thedata terminals DQ, DBI, and DMI according to the WCK and WCKF clocksignals. The write command may be received by the command decoder 115,which can provide internal commands to the input/output circuit 160 sothat the write data can be received by data receivers in theinput/output circuit 160, and supplied via the input/output circuit 160and the read/write amplifiers 155 to the memory array 150. The writedata may be written in the memory cell designated by the row address andthe column address. The write data may be provided to the data terminalsat a time that is defined by write latency WL information. The writelatency WL information can be programmed in the memory device 100, forexample, in the mode register (not shown in FIG. 1). The write latencyWL information can be defined in terms of clock cycles of the CK clocksignal. For example, the write latency information WL can be a number ofclock cycles of the CK signal after the write command is received by thememory device 100 when the associated write data is received.

The power supply terminals may be supplied with power supply potentialsVDD and VSS. These power supply potentials VDD and VSS can be suppliedto an internal voltage generator circuit 170. The internal voltagegenerator circuit 170 can generate various internal potentials VPP, VOD,VARY, VPERI, and the like based on the power supply potentials VDD andVSS. The internal potential VPP can be used in the row decoder 140, theinternal potentials VOD and VARY can be used in the sense amplifiersincluded in the memory array 150, and the internal potential VPERI canbe used in many other circuit blocks.

The power supply terminal may also be supplied with power supplypotential VDDQ. The power supply potential VDDQ can be supplied to theinput/output circuit 160 together with the power supply potential VSS.The power supply potential VDDQ can be the same potential as the powersupply potential VDD in an embodiment of the present technology. Thepower supply potential VDDQ can be a different potential from the powersupply potential VDD in another embodiment of the present technology.However, the dedicated power supply potential VDDQ can be used for theinput/output circuit 160 so that power supply noise generated by theinput/output circuit 160 does not propagate to the other circuit blocks.

The clock terminals and data clock terminals may be supplied withexternal clock signals and complementary external clock signals. Theexternal clock signals CK, CKF, WCK, WCKF can be supplied to a clockinput circuit 120. The CK and CKF signals can be complementary, and theWCK and WCKF signals can also be complementary. Complementary clocksignals can have opposite clock levels and transition between theopposite clock levels at the same time. For example, when a clock signalis at a low clock level a complementary clock signal is at a high level,and when the clock signal is at a high clock level the complementaryclock signal is at a low clock level. Moreover, when the clock signaltransitions from the low clock level to the high clock level thecomplementary clock signal transitions from the high clock level to thelow clock level, and when the clock signal transitions from the highclock level to the low clock level the complementary clock signaltransitions from the low clock level to the high clock level.

Input buffers included in the clock input circuit 120 can receive theexternal clock signals. For example, when enabled by a CKE signal fromthe command decoder 115, an input buffer can receive the CK and CKFsignals and the WCK and WCKF signals. The clock input circuit 120 canreceive the external clock signals to generate internal clock signalsICLK. The internal clock signals ICLK can be supplied to an internalclock circuit 130. The internal clock circuit 130 can provide variousphase and frequency controlled internal clock signal based on thereceived internal clock signals ICLK and a clock enable signal CKE fromthe command/address input circuit 105. For example, the internal clockcircuit 130 can include a clock path (not shown in FIG. 1) that receivesthe internal clock signal ICLK and provides various clock signals to thecommand decoder 115. The internal clock circuit 130 can further provideinput/output (IO) clock signals. The IO clock signals can be supplied tothe input/output circuit 160 and can be used as a timing signal fordetermining an output timing of read data and the input timing of writedata. The IO clock signals can be provided at multiple clock frequenciesso that data can be output from and input to the memory device 100 atdifferent data rates. A higher clock frequency may be desirable whenhigh memory speed is desired. A lower clock frequency may be desirablewhen lower power consumption is desired. The internal clock signals ICLKcan also be supplied to a timing generator 135 and thus various internalclock signals can be generated.

Memory devices such as the memory device 100 of FIG. 1 can providememory capacity with multiple memory arrays, or with a single array thatis sub-divided into multiple separately-addressable portions (e.g., intomultiple channels, banks, ranks, etc.). Alternatively, a memory systemcan include multiple memory devices such as the memory device 100 ofFIG. 1, where each memory device represents a separately-addressablesub-division (e.g., rank, etc.) of the memory capacity of the system.Accordingly, a memory device or a memory system with multiple memorydevices, ranks, channels, banks or the like can include multipleterminals (e.g., clock terminals, CMD/ADD terminals, I/O terminals,etc.) that are dedicated to one or more, but less than all of, theseparately-addressable portions. For example, a multi-channel memorydevice can include multiple terminals, each corresponding to one of themultiple channels of memory. When operating such a memory device, toreduce undesirable noise on a common signal path (e.g., a clock path, adata bus, etc.), the memory device can utilize on-die termination toprovide proper impedance at those terminals of the memory devicecorresponding to the separately-addressable portions of memory that arenot communicating on the common signal path. For example, when aconnected host or memory controller accesses a first channel of thememory device, terminals of the memory device corresponding to a secondchannel can be provided with proper impedance by on-die terminationcircuitry (e.g., integral to a corresponding i/o circuit 160, clockinput circuit 120, or the like).

One approach to initiating on-die termination includes a host providinga signal (e.g., via a dedicated or shared pin or terminal) or command(e.g., via the command/address bus) to the non-targeted portion of thememory device to provide termination during a communication performed bya targeted portion of the memory device. For example, a command on ashared command/address bus can indicate to both the targeted andnon-targeted portion that a communication (e.g., a read operation, awrite operation, an erase operation, a status inquiry operation, etc.)is to be performed, while dedicated chip select terminals for eachportion can indicate which portion is targeted (e.g., by a pulse lastinga single clock cycle) and which is non-targeted (e.g., by a pulselasting two clock cycles). Such an approach is illustrated schematicallyin the timing diagram 200 of FIG. 2, in accordance with one aspect ofthe present technology.

As can be seen with reference to FIG. 2, in a memory device or systemwith two or more separately-addressable portions (e.g., two channels ofa memory device, two memory devices of a memory system, etc.), a commoncommand/address bus 220 can be used to indicate to the portions that acommunication is to be performed by one of the portions (e.g., via aread command). A dedicated chip select terminal for each portion (e.g.,CS_A 230 and CS_B 240) can be used to provide an indication to eachportion whether it is targeted or non-targeted for the communication. Inresponse to receiving an indication that is not the target of a commandto communicate, the non-targeted portion can enter an on-die terminationmode for the duration of the communication. In this regard, the timingdiagram 200 of FIG. 2 illustrates a sequence of read commands targetingdifferent channels of a memory device.

As illustrated, the first read command 221 is sent with correspondingindications 231 and 241 on the chip select terminals 230 and 240 thatthe target of the first read command corresponds to the first channel250 of the memory device (e.g., by pulsing a chip select line low forone cycle of a clock 210 to indicate the targeted portion, and for twocycles of the clock 210 to indicate the non-targeted portion).Accordingly, the second channel 260 of the memory device enters anon-die termination mode 261 for the duration of a communication 251 ofthe first channel 250. Following the communication 251, the secondchannel 260 returns to a default or “parked” mode of impedance. A secondread command 222 is similarly sent with corresponding indications 232and 242 on the chip select terminals 230 and 240 that the target of thesecond read command corresponds to the first channel 250 of the memorydevice. Accordingly, the second channel 260 of the memory device entersan on-die termination mode 262 for the duration of a communication 252of the first channel 250. Following the communication 252, the secondchannel 260 returns to the parked mode of impedance. A third readcommand 223 is sent with corresponding indications 233 and 243 on thechip select terminals 230 and 240 that the target of the third readcommand corresponds to the second channel 260 of the memory device.Accordingly, the first channel 250 of the memory device enters an on-dietermination mode 253 for the duration of a communication 263 of thesecond channel 260. Following the communication 263, the first channel250 returns to the parked mode of impedance.

A drawback to this approach of providing on-die termination commands toa non-targeted memory portion with each command to a targeted portion(e.g., with a corresponding indication on a chip select terminal) isthat the non-targeted memory portion consumes power in decoding eachcommand. In this regard, the command decoder of a memory device (e.g.,command decoder 115) may be configured to “wake up” (e.g., to deliverpower or signal voltages to one or more components previously in ano-power, low-power, or signal-disconnected state) in response topulsing a corresponding chip select line low (e.g., whether for one ortwo clock cycles). Moreover, alternating the impedance from a parkedmode to a termination mode (e.g., a read termination mode, a writetermination mode, etc.) and back may further consume additional power.Accordingly, embodiments of the present technology may solve theforegoing problems by providing on-die termination at a non-targetedmemory portion without the power consumption caused by decoding anon-targeted communication (e.g., read, write, status, etc.) command.Rather, in one embodiment, a memory portion can be configured to provideon-die termination in response to a command received in connection witha previous communication command.

Turning to FIG. 3, a simplified timing diagram 300 schematicallyillustrates the operation of a memory system in accordance with anembodiment of the present technology. As can be seen with reference toFIG. 3, in a memory device or system with two or moreseparately-addressable portions (e.g., two channels of a memory device,two memory devices of a memory system), a common command/address bus 320can be used to indicate to the portions that a communication is to beperformed by one of the portions (e.g., via a read command). Unlike theapproach illustrated in FIG. 2, however, in the approach illustrated inFIG. 3, in response to an indication to a memory portion that it is notthe target of a communication, the memory portion enters and remains inan on-die termination mode until receiving a subsequent indication orcommand to exit the on-die termination mode.

In the example of FIG. 3, a first read command 321 is sent withcorresponding indications 331 and 341 on the chip select terminals 330and 340 that the target of the first read command corresponds to thefirst channel 350 of the memory device (e.g., by pulsing a chip selectline low for one cycle of a clock 310 to indicate the targeted portion,and for two cycles of the clock 310 to indicate the non-targetedportion). Accordingly, the second channel 360 of the memory deviceenters an on-die termination mode 361 for the duration of acommunication 351 of the first channel 350. Rather than returning to aparked mode of impedance following the completion of the communication351, however, the second channel 360 remains in the on-die terminationmode 361. Accordingly, during subsequent communications for which thesecond channel remains non-targeted, no further indications need be sentto nor commands decoded by the second channel to provide on-dietermination thereat.

For example, as can be seen with reference to FIG. 3, a second readcommand 322 is sent with an indication 332 on the chip select terminal330 that the target of the second read command corresponds to the firstchannel 350 of the memory device. No indication is sent on the chipselect terminal 340 corresponding to the second channel 360, however,ensuring that the command decoder of the second channel need not consumepower processing the command 322. Rather, the second channel 360 of thememory device remains in the on-die termination mode 361 initiated forthe earlier communication 351, and continues to provide termination forthe duration of a communication 352 of the first channel 350. When athird read command 323 is subsequently sent with correspondingindications 333 and 343 on the chip select terminals 330 and 340 thatthe target of the third read command corresponds to the second channel360 of the memory device (e.g., by pulsing a chip select line low forone cycle of a clock 310 to indicate the targeted portion, and for twocycles of the clock 310 to indicate the non-targeted portion), thesecond channel 360 of the memory device exits the on-die terminationmode 361 and performs the communication 363, and the first channel 350of the memory device enters an on-die termination mode 353 (e.g., andmay be, like the second channel 360, configured to remain therein untilreceiving a command to exit the on-die termination mode 353).

Although in the foregoing example embodiment, the on-die terminationmode 361 is illustrated and described as persisting for the duration oftwo communications, in other embodiments a persistent on-die terminationmode can last for many more communications (e.g., and/or for extendedperiods during which no communication are taking place). In this regard,a persistent on-die termination mode can be configured to persist untila command (e.g., a communication command targeting the memory portionproviding termination, or a command to exit the termination mode withoutcommunicating) is received. For each communication for which a memoryportion provides termination without requiring the consumption of powerin decoding an on-die termination command, the power savings of thepresent approach will be increased, as compared to the approachillustrated in FIG. 2.

In accordance with another aspect of the present disclosure, apersistent on-die termination mode can remain in effect until one ormore of a number of different criteria for ending the mode are met. Inthis regard, a persistent on-die termination can be configured topersist until the receipt of (i) a read command targeting the addressedto the memory portion, (ii) a write command addressed to the terminatedmemory portion, (iii) a non-targeted termination command addressed tothe memory portion (e.g., with a different termination level), (iv) acommand to exit the termination mode, or (v) a self-refresh command. Inone embodiment, a command to exit the termination mode (a “TermOFF”command) can be executed based on a predetermined delay (e.g., asconfigured in a predetermined mode register) to facilitate scheduling.In some embodiments, a TermOFF command can be provided immediatelyfollowing a column access select (“CAS”) command to a different memoryportion, such that execution of the TermOFF command following thepredetermined delay can ensure a change in the termination modecorresponds in time with the execution of the CAS command. The TermOFFcommand can be either a single-clock-cycle command or amultiple-clock-cycle command.

Turning to FIG. 4, a simplified timing diagram 400 schematicallyillustrates the operation of a memory system in accordance with anotherembodiment of the present technology. As can be seen with reference toFIG. 4, in a memory device or system with two or moreseparately-addressable portions (e.g., two channels of a memory device,two memory devices of a memory system), a common command/address bus 420can be used to indicate to the portions that a communication is to beperformed by one of the portions (e.g., via a read command). Unlike theapproach illustrated in FIG. 3, however, in the approach illustrated inFIG. 4, in response to an indication to a memory portion that it is notthe target of a communication, the memory portion enters an on-dietermination mode to which it reverts following subsequent commands tocommunicate (e.g., unless instructed otherwise).

In the example of FIG. 4, a first read command 421 is sent withcorresponding indications 431 and 441 on the chip select terminals 430and 440 that the target of the first read command corresponds to thefirst channel 450 of the memory device (e.g., by pulsing a chip selectline low for one cycle of a clock 410 to indicate the targeted portion,and for two cycles of the clock 410 to indicate the non-targetedportion). Accordingly, the second channel 460 of the memory deviceenters an on-die termination mode 461 at least for the duration of acommunication 451 of the first channel 450. When a second read command422 is sent with indications 431 and 432 on the chip select terminals430 and 440 that the target of the second read command corresponds tothe second channel 460 of the memory device, the first channel 450 ofthe memory device enters an on-die termination mode 452 at least for theduration of a communication 462 of the second channel 460. Because thesecond channel 460 is configured to revert to its previous on-dietermination mode following the completion of the communication 462, nosubsequent indication need be sent on the corresponding chip selectterminal 440, and the second channel 460 of the memory device reverts toan on-die termination mode 463 rather than a parked mode of termination.Accordingly, when a third read command 423 is sent with an indication433 on the chip select terminal 430 that the target of the third readcommand corresponds to first channel 450 of the memory device, noindication is sent on the second chip select terminal 440, as the secondchannel 460 has already reverted to the on-die termination mode 463,which provides the desired termination while the first channel 450 ofthe memory device performs the commanded communication 453.

Although in the foregoing example embodiments, the communicationsperformed by one memory portion while another is in an on-dietermination mode have been described and illustrated as read operations(e.g., with corresponding read levels of on-die termination), in otherembodiments of the present technology, the foregoing and followingapproaches can similarly be applied to other communications (e.g., writeoperations, status operations, etc.), with corresponding levels oftermination (e.g., non-targeted write level termination, non-targetedstatus level termination, etc.).

For example, turning to FIG. 5, a simplified timing diagram 500schematically illustrates the operation of a memory system in accordancewith another embodiment of the present technology. As can be seen withreference to FIG. 5, in a memory device or system with two or moreseparately-addressable portions (e.g., two channels of a memory device,two memory devices of a memory system), a common command/address bus 520can be used to indicate to the portions that a communication is to beperformed by one of the portions (e.g., via a write command).

In the approach illustrated in FIG. 5, in response to an indication to amemory portion that it is not the target of a communication, the memoryportion enters an on-die termination mode in which it remains for anindicated duration (e.g., for an indicated number of subsequentcommunications). In this regard, a first write command 521 is sent withcorresponding indications 531 and 541 on the chip select terminals 530and 540 that the target of the first read command corresponds to thefirst channel 550 of the memory device (e.g., by pulsing a chip selectline low for one cycle of a clock 510 to indicate the targeted portion,and for two cycles of the clock 510 to indicate the non-targetedportion). The write command 521 can include an indication (e.g., inotherwise-unused bits on the command/address bus 520) to thenon-targeted portion of the memory device to provide on-die terminationfor a number of subsequent communications (e.g., in the illustratedexample, for two communications). Accordingly, the second channel 560 ofthe memory device enters an on-die termination mode 561 and the firstchannel 550 performs a communication 551 (e.g., the requested writeoperation).

In the example of FIG. 5, a second write command 522 is sent with anindication 531 on the chip select terminal 530 that the target of thesecond write command corresponds to the first channel 550 of the memorydevice. Because the second channel 560 was previously commanded (e.g.,by write command 521) to remain in the on-die termination mode 561 forthe duration of two communication events, no subsequent indication needbe sent on the corresponding chip select terminal 540, and the secondchannel 560 continues to provide termination during the secondcommunication 552. Following the completion of the second communication552, the on-die termination mode 561 is exited, and the second channelreverts to a default “parked” mode of termination. When a third readcommand 523 is sent with corresponding indications 533 and 543 on thechip select terminals 530 and 540 that the target of the third readcommand corresponds to the second channel 560 of the memory device, thefirst channel 550 of the memory device enters an on-die termination mode553 for the duration of a communication 563 of the second channel 560.Following the termination mode 553, the first channel 550 returns to theparked mode of impedance.

According to one aspect of the present technology, the various foregoingapproaches (e.g., persisting in an on-die termination mode, reverting toan on-die termination mode, and commanding an on-die termination mode tolast for more than one communication) can be combined in a variety ofways to provide additional approaches. For example, the approach ofreverting to a previous on-die termination mode can be combined with theapproach of instructing on-die termination to last for a predeterminednumber of communications (e.g., by instructing a memory portion toprovide write-level on-die termination for three communications, afterwhich the memory portion reverts to a previous on-die termination mode,such as a read-level on-die termination).

Although in the foregoing example embodiments, memory devices andsystems with just two memory portions (e.g., and just two correspondingchip select terminals) have been illustrated, the foregoing approachesto on-die termination have application to memory devices and systemswith more than two channels or other sub-addressable portions. As willbe readily understood by those skilled in the art, the power-savingbenefits of these approaches will be even greater for devices in whichmore on-die termination commands corresponding to a single communicationcommand can be omitted.

FIG. 6 is a simplified block diagram schematically illustrating a memorysystem 600 in accordance with an embodiment of the present technology.Memory system 600 includes a host device 610 operably coupled to amemory module 620 (e.g., a dual in-line memory module (DIMM)). Memorymodule 620 can include a controller 630 operably connected by a bus 640to a plurality of memory devices 650. In accordance with one embodimentof the present disclosure, the host device 610 can communicate with afirst one of the memory devices 650 (e.g., via a read command, a writecommand, etc. communicated over the bus 640), and with one or more ofthe other memory devices 650 to transmit an on-die termination signal(e.g., such as on-die termination signal 341 in timing diagram 300,on-die termination signal 441 in timing diagram 400, or on-dietermination signal 541 in timing diagram 500). In an alternativeembodiment, the controller 630 can communicate with a first one of thememory devices 650 (e.g., via a read command, a write command, etc.communicated over the bus 640), and with one or more of the other memorydevices 650 to transmit an on-die termination signal (e.g., such ason-die termination signal 341 in timing diagram 300, on-die terminationsignal 441 in timing diagram 400, or on-die termination signal 541 intiming diagram 500). In this regard, the controller 630 can intermediatebetween the host device 610 (e.g., which may send a communication (e.g.,read, write, etc.) command to a targeted memory device concurrently withan ODT command directed at the non-targeted memory devices) and thememory devices 650 to provide the command to the targeted memory devicewith either a modified ODT command (e.g., indicating a durationcorresponding to multiple communication events) or without providing theODT command to the other memory devices (e.g., relying instead on thenon-targeted memory device to either remain in a previously-commandedODT mode or to revert to a previously-commanded ODT mode).

FIG. 7 is a flow chart illustrating a method of operating a memorysystem in accordance with an embodiment of the present technology. Themethod includes receiving a first command instructing a first memorydevice of the memory system to perform a first communication andinstructing a second memory device of the memory system to enter anon-die termination mode (box 710). According to one aspect of thepresent disclosure, the command receiving features of box 710 may beimplemented with a command/address input circuit 105 and/or terminalsconnected thereto, as illustrated in FIG. 1 in greater detail, above.

The method further includes performing, with the first memory device,the first communication while the second memory device is in the on-dietermination mode based at least in part on the first command (box 720).According to one aspect of the present disclosure, the communicationfeatures of box 720 may be implemented with a memory array 150, decoders(e.g., address decoder 110, command decoder 115, row decoder 140, columndecoder 145, etc.) connected thereto, and/or IO circuit 160, asillustrated in FIG. 1 in greater detail, above.

The method further includes receiving a second command instructing thefirst memory device to perform a second communication with the memoryhost (box 730), and performing, with the first memory device, the secondcommunication while the second memory device is in the on-dietermination mode based at least in part on the first command (box 740).According to one aspect of the present disclosure, the command receivingand communication features of boxes 730 and 740 may be implemented witha command/address input circuit 105 and/or terminals connected thereto,a memory array 150, decoders (e.g., address decoder 110, command decoder115, row decoder 140, column decoder 145, etc.) connected thereto,and/or IO circuit 160, as illustrated in FIG. 1 in greater detail,above.

FIG. 8 is a flow chart illustrating a method of operating a memorydevice in accordance with an embodiment of the present technology. Themethod includes receiving a first command at the memory deviceinstructing the first portion to perform a first communication andinstructing the second portion to enter an on-die termination mode (box810). According to one aspect of the present disclosure, the commandreceiving features of box 810 may be implemented with a command/addressinput circuit 105 and/or terminals connected thereto, as illustrated inFIG. 1 in greater detail, above.

The method further includes maintaining, at the second portion, theon-die termination mode until receiving a second command instructing thesecond portion to exit the on-die termination mode (box 820). Accordingto one aspect of the present disclosure, the on-die termination modemaintaining features of box 820 may be implemented with acommand/address input circuit 105, a clock input circuit 120, an IOcircuit 160, and/or any terminals connected thereto, as illustrated inFIG. 1 in greater detail, above.

FIG. 9 is a flow chart illustrating a method of operating a memorydevice in accordance with an embodiment of the present technology. Themethod includes receiving a command at the memory device instructing afirst portion of the memory device to perform a communication (box 910).According to one aspect of the present disclosure, the command receivingfeatures of box 910 may be implemented with a command/address inputcircuit 105 and/or terminals connected thereto, as illustrated in FIG. 1in greater detail, above.

The method further includes performing the communication at the firstportion of the memory device (box 920), and reverting, at the firstportion of the memory device, to an on-die termination mode active atthe first portion prior to performing the communication (box 930).According to one aspect of the present disclosure, the communicationperforming features and on-die termination mode reverting features ofboxes 920 and 930 may be implemented with a memory array 150, decoders(e.g., address decoder 110, command decoder 115, row decoder 140, columndecoder 145, etc.) connected thereto, input circuits (e.g.,command/address input circuit 105, clock input circuit 120, etc.),and/or IO circuit 160, as illustrated in FIG. 1 in greater detail,above.

FIG. 10 is a flow chart illustrating a method of operating a memorydevice in accordance with an embodiment of the present technology. Themethod includes receiving a command at the memory device instructing afirst portion of the memory device to perform a communication having afirst duration and instructing a second portion of the memory device toenter an on-die termination mode having a second duration (box 1010).According to one aspect of the present disclosure, the command receivingfeatures of box 1010 may be implemented with a command/address circuit105 and/or terminals connected thereto, as illustrated in FIG. 1 ingreater detail, above.

The method further includes performing the communication at the firstportion of the memory device (box 1020), and maintaining, at the secondportion, the on-die termination mode for the second duration, whereinthe second duration is greater than the first duration (box 1030).According to one aspect of the present disclosure, the communicationperforming features and on-die termination mode maintaining features ofboxes 1020 and 1030 may be implemented with a memory array 150, decoders(e.g., address decoder 110, command decoder 115, row decoder 140, columndecoder 145, etc.) connected thereto, input circuits (e.g.,command/address input circuit 105, clock input circuit 120, etc.),and/or IO circuit 160, as illustrated in FIG. 1 in greater detail,above.

It should be noted that the methods described above describe possibleimplementations, and that the operations and the steps may be rearrangedor otherwise modified and that other implementations are possible.Furthermore, embodiments from two or more of the methods may becombined.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof. Some drawings may illustrate signals as a single signal;however, it will be understood by a person of ordinary skill in the artthat the signal may represent a bus of signals, where the bus may have avariety of bit widths.

The devices discussed herein, including a memory device, may be formedon a semiconductor substrate or die, such as silicon, germanium,silicon-germanium alloy, gallium arsenide, gallium nitride, etc. In somecases, the substrate is a semiconductor wafer. In other cases, thesubstrate may be a silicon-on-insulator (SOI) substrate, such assilicon-on-glass (SOG) or silicon-on-sapphire (SOP), or epitaxial layersof semiconductor materials on another substrate. The conductivity of thesubstrate, or sub-regions of the substrate, may be controlled throughdoping using various chemical species including, but not limited to,phosphorous, boron, or arsenic. Doping may be performed during theinitial formation or growth of the substrate, by ion-implantation, or byany other doping means.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Otherexamples and implementations are within the scope of the disclosure andappended claims. Features implementing functions may also be physicallylocated at various positions, including being distributed such thatportions of functions are implemented at different physical locations.

As used herein, including in the claims, “or” as used in a list of items(for example, a list of items prefaced by a phrase such as “at least oneof” or “one or more of”) indicates an inclusive list such that, forexample, a list of at least one of A, B, or C means A or B or C or AB orAC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase“based on” shall not be construed as a reference to a closed set ofconditions. For example, an exemplary step that is described as “basedon condition A” may be based on both a condition A and a condition Bwithout departing from the scope of the present disclosure. In otherwords, as used herein, the phrase “based on” shall be construed in thesame manner as the phrase “based at least in part on.”

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thescope of the invention. Rather, in the foregoing description, numerousspecific details are discussed to provide a thorough and enablingdescription for embodiments of the present technology. One skilled inthe relevant art, however, will recognize that the disclosure can bepracticed without one or more of the specific details. In otherinstances, well-known structures or operations often associated withmemory systems and devices are not shown, or are not described indetail, to avoid obscuring other aspects of the technology. In general,it should be understood that various other devices, systems, and methodsin addition to those specific embodiments disclosed herein may be withinthe scope of the present technology.

What is claimed is:
 1. A method of operating a memory system,comprising: receiving a first command instructing a first memory deviceof the memory system to perform a first communication with a memory hostand instructing a second memory device of the memory system to enter anon-die termination mode; performing, with the first memory device, thefirst communication while the second memory device is in the on-dietermination mode based at least in part on the first command; receivinga second command instructing the first memory device to perform a secondcommunication with the memory host; and performing, with the firstmemory device, the second communication while the second memory deviceis in the on-die termination mode based at least in part on the firstcommand.
 2. The method of claim 1, further comprising: receiving a thirdcommand instructing the second memory device of the memory system toexit the on-die termination mode; and the second memory device of thememory system exiting the on-die termination mode based at least in parton the third command.
 3. The method of claim 1, further comprising: thesecond memory device of the memory system remaining, based at least inpart on the first command, in the on-die termination mode for a durationgreater than that of the first communication.
 4. The method of claim 3,wherein the first command includes a number of bursts or clock cyclesfor which the second memory device is to remain in the on-dietermination mode.
 5. The method of claim 1, further comprising:receiving a third command subsequent to the first command and prior tothe second command, the third command instructing the second memorydevice to perform a third communication and the first memory device toenter the on-die termination mode; and performing, with the secondmemory device, the third communication while the first memory device isin the on-die termination mode based at least in part on the secondcommand, reverting, based at least in part on the first command, thesecond memory device to the on-die termination mode after performing thethird communication.
 6. The method of claim 1, wherein the secondcommand is subsequent to the first command.
 7. The method of claim 1,wherein the first communication is one of a read or a write operation.8. The method of claim 1, wherein a single semiconductor die comprisesthe first memory device and the second memory device.
 9. A method ofoperating a memory device including a first portion and a secondportion, the method comprising: receiving a first command at the memorydevice instructing the first portion to perform a first communicationand instructing the second portion to enter an on-die termination mode;receiving a second command instructing the second portion to exit theon-die termination mode; and maintaining, at the second portion, theon-die termination mode based at least in part on the first commanduntil receiving the second command.
 10. The method of claim 9, whereinthe first portion corresponds to a first channel of the memory device,and wherein the second portion corresponds to a second channel of thememory device.
 11. The method of claim 9, further comprising: performingthe first communication, wherein the second portion remains in theon-die termination mode after performing the first communication.
 12. Amemory device, comprising: a first memory portion; a second memoryportion; and circuitry configured to implement an on-die terminationmode at the second memory portion; wherein the circuitry is configured,in response to a single command to the second memory portion, toimplement the on-die termination mode at the second memory portionduring more than one communication at the first memory portion.
 13. Thememory device of claim 12, wherein the circuitry is configured toimplement the on-die termination mode at the second memory portion inresponse to a first command to implement the on-die termination mode,and to remain in the on-die termination mode until receiving a secondcommand to exit the on-die termination mode.
 14. The memory device ofclaim 12, wherein the circuitry is configured to implement the on-dietermination mode at the second memory portion until a threshold numberof communications are performed at the first memory portion, wherein thethreshold number is indicated in the single command to the second memoryportion.
 15. The memory device of claim 12, wherein the circuitry isconfigured to implement the on-die termination mode at the second memoryportion in response to a first command instructing the first memoryportion to perform a communication and instructing the second memoryportion to enter the on-die termination mode, and to revert to theon-die termination mode following a communication at the second memoryportion.
 16. A memory device, comprising: a first memory portion; asecond memory portion; and circuitry configured to: implement an on-dietermination mode at the second memory portion in response to receiving afirst command; and to exit the on-die termination mode in response toreceiving a second command subsequent to the first command.
 17. Thememory device of claim 16, wherein the first memory portion correspondsto a first channel of the memory device, and wherein the second memoryportion corresponds to a second channel of the memory device.
 18. Amethod of operating a memory system, comprising: transmitting a firstcommand instructing a first memory device of the memory system toperform a first communication with a memory host and instructing asecond memory device of the memory system to enter an on-die terminationmode; performing, with the first memory device, the first communicationwhile the second memory device is in the on-die termination mode basedat least in part on the first command; transmitting a second commandinstructing the first memory device to perform a second communicationwith the memory host; and performing, with the first memory device, thesecond communication while the second memory device is in the on-dietermination mode based at least in part on the first command.
 19. Themethod of claim 18, further comprising: transmitting a third commandinstructing the second memory device of the memory system to exit theon-die termination mode; and the second memory device of the memorysystem exiting the on-die termination mode based at least in part on thethird command.
 20. The method of claim 18, further comprising: thesecond memory device of the memory system remaining, based at least inpart on the first command, in the on-die termination mode for a durationgreater than that of the first communication.
 21. The method of claim20, wherein the first command includes a number of bursts or clockcycles for which the second memory device is to remain in the on-dietermination mode.
 22. The method of claim 18, further comprising:transmitting a third command subsequent to the first command and priorto the second command, the third command instructing the second memorydevice to perform a third communication and the first memory device toenter the on-die termination mode; and performing, with the secondmemory device, the third communication while the first memory device isin the on-die termination mode based at least in part on the secondcommand, reverting, based at least in part on the first command, thesecond memory device to the on-die termination mode after performing thethird communication.
 23. The method of claim 18, wherein the secondcommand is subsequent to the first command.
 24. The method of claim 18,wherein the first communication is one of a read or a write operation.25. The method of claim 18, wherein a single semiconductor die comprisesthe first memory device and the second memory device.